JPH1050335A - Manufacture of electrode support tube for cylindrical type solid electrolyte fuel battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electrode support tube with superior circularity and straightness and even void rate. SOLUTION: In this method, a non-sintered molder 10 is received on a support member 11 in its free state and is sintered, whereby the thermal expansion and contraction can be arbitrarily performed, a load distribution does not deviate, and void rate is uniform over full length while maintaining circularity and straightness. A powder 13 with the same composition as the electrode support tube is laid on an inner circumference of the support member 11, whereby chemical reaction occurs between the support member surface and the electrode support tube surface during high-temperature sintering, so that the molder 10 and the support member 11 are not in contact with each other, and electrochemical characteristics of the electrode support tube is prevented in advance from being damaged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an electrode support tube of a cylindrical solid electrolyte fuel cell.

[0002]

2. Description of the Related Art A cylindrical solid electrolyte fuel cell having a structure in which an inner electrode itself is a support tube generally has a structure shown in FIG. A, and a porous lanthanum manganite (La (Sr) MnOn) is sequentially arranged from the inside. Air electrode 1, solid electrolyte 2 made of yttria-stabilized zirconia (YSZ), cermet fuel electrode 3 made of nickel or nickel alloy and YSZ
The interconnector 4 is arranged on a part of the outer peripheral surface so as to be insulated from the fuel electrode 3 and to be connected to the internal air electrode 1.

In the cylindrical solid electrolyte fuel cell having such a structure, an inner air electrode tube (hereinafter, referred to as an electrode support tube) which also serves as a cell support tube (substrate tube) has a solid electrolyte film formed on its outer periphery. In addition, it is necessary to form a fuel electrode further on the outside, and it is necessary that a large number of porous pores are uniformly distributed throughout, the porosity is uniform, and the straightness and the roundness are high. Required.

Some solid electrolyte fuel cells have a structure in which an air electrode is disposed on the outside and a solid electrolyte and a fuel electrode are sequentially formed on the inside. In this case, the outside air electrode is used as an electrode support tube. Since the fuel cell is manufactured by a method in which a solid electrolyte and a fuel electrode are sequentially formed on the inner side, the porosity of the innumerable porous holes in the electrode support tube is also uniform in the same manner,
And it is required to have high straightness and roundness.

Therefore, conventionally, in order to form such an electrode support tube, a fine powder of a lanthanum strontium manganese-based perovskite crystal structure as an electrode material is kneaded with water and a binder to form a clay, which is extruded. Then, a cylindrical electrode support tube molded body is obtained by drying, and dried to remove water and solidify to obtain a self-shape-preserving state.
The method of raising the temperature to about 500 ° C. and firing is employed.

[0006]

However, in such a conventional method for manufacturing an electrode support tube of a cylindrical solid electrolyte fuel cell, the electrode support tube molded body is suspended in a firing furnace and fired. Although an electrode support tube excellent in straightness and roundness could be formed, there were the following problems.

That is, when the molded body is suspended in the air, the upper part of the molded body is suspended by a jig, and the lower part is free and vertically supported and fired. Due to the gravitational load applied, the hole diameter is wider than that of the lower part, and the porosity (ratio of the opening area per unit area) is large in the upper part and small in the lower part. There was a problem.

The present invention has been made in view of such conventional problems, and has been made in view of the above. An electrode of a cylindrical solid electrolyte fuel cell capable of maintaining straightness and roundness and having a uniform porosity as a whole is provided. An object of the present invention is to provide a method for manufacturing a support tube.

[0009]

According to a first aspect of the present invention, there is provided a method for manufacturing an electrode support tube for a cylindrical solid electrolyte fuel cell, comprising a semi-circular, long, high heat-resistant material fixed horizontally in a firing furnace. On the inner peripheral surface of the support member, a powder of approximately the same composition as the target electrode support tube is laid, and the unfired molded body that becomes the electrode support tube by a firing process is held by the support member in a free state, By raising the temperature of the firing furnace, the molded body is fired to obtain the electrode support tube.

In the method for manufacturing an electrode support tube of a cylindrical solid electrolyte fuel cell according to the first aspect, the unsintered compact is supported on the support member in a free state and is sintered, so that thermal expansion and contraction can be freely performed. As a result, the load distribution is not biased, and the porosity can be made uniform over the entire length while maintaining the roundness and straightness.

Further, by laying powder having the same composition as the electrode support tube on the inner periphery of the support member, the compact and the support member do not come into direct contact with each other. Thus, a problem that a chemical reaction occurs to impair the electrochemical characteristics of the electrode support tube can be prevented.

According to a second aspect of the present invention, there is provided a method for manufacturing an electrode support tube for a cylindrical solid electrolyte fuel cell, comprising a support made of a high heat-resistant material having a semicircular cross section and fixed in a firing furnace at a predetermined inclination angle. On the inner peripheral surface of the member, a powder of a composition substantially the same as the intended electrode support tube is laid, and the unfired molded body that becomes the electrode support tube by a firing process is held by the support member in a free state, By heating the firing furnace, the molded body is fired to obtain the electrode support tube.

In the method for manufacturing an electrode support tube of a cylindrical solid electrolyte fuel cell according to the second aspect of the present invention, the green body is held in a free state on a support member fixed at a predetermined inclination angle. Since it is fired, the long molded body expands thermally,
The frictional resistance acting on the material during contraction can be reduced, and the porosity can be made uniform over the entire length while maintaining the roundness and straightness.

According to a third aspect of the present invention, there is provided the method for manufacturing an electrode support tube of a cylindrical solid electrolyte fuel cell according to the first or second aspect, wherein the compact comprises a lanthanum manganese-based fine powder having a perovskite crystal structure, water and a binder. The raw material kneaded into a clay is formed into a tubular shape, and dried to remove water to use.

In the method for manufacturing an electrode support tube of a cylindrical solid electrolyte fuel cell according to the third aspect of the present invention, an electrode support tube made of a lanthanum manganese oxide ceramic having excellent electrochemical characteristics can be obtained as a fuel cell electrode. .

According to a fourth aspect of the present invention, in the method for manufacturing an electrode support tube of a cylindrical solid electrolyte fuel cell according to the third aspect, a ceramic powder of a lanthanum manganese-based oxide is used as the powder to be spread on the support member.

In the method for manufacturing an electrode support tube of a cylindrical solid electrolyte fuel cell according to the present invention, a powder having substantially the same composition as that of the electrode support tube is interposed between the molded body serving as the electrode support tube and the support member. Therefore, it is possible to reliably prevent a chemical reaction from occurring with the surface of the supporting member during high-temperature firing, and to obtain a good surface state.

According to a fifth aspect of the present invention, in the method for manufacturing an electrode support tube of a cylindrical solid electrolyte fuel cell according to the fourth aspect, the particle size of the powder to be spread on the support member is smaller than the particle size of the powder of the green body raw material. A coarse one is used.

In the method for manufacturing an electrode support tube of a cylindrical solid electrolyte fuel cell according to the present invention, the particle diameter of the powder spread on the support member is made larger than the particle diameter of the powder of the raw material of the compact. It is possible to prevent the powder laid on the support member from reacting with the surface of the electrode support tube during the high-temperature firing, and to improve the electrochemical characteristics of the electrode support tube.

According to a sixth aspect of the present invention, there is provided the method for manufacturing an electrode support tube of a cylindrical solid electrolyte fuel cell according to any one of the first to fifth aspects, wherein the supporting member is made of stabilized zirconia, magnesia, alumina or a mixture thereof. Heat-resistant ceramics are used.

In the method for manufacturing an electrode support tube of a cylindrical solid electrolyte fuel cell according to the present invention, the support member is made of heat-resistant ceramics of stabilized zirconia, magnesia, alumina or a mixture thereof.
The surface state is stable during high-temperature firing, and the electrochemical characteristics of the electrode support tube can be further improved in combination with the powder interposed between the electrode support tube and the compact.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. Fine powder of lanthanum strontium manganese La (Sr) MnOn having a perovskite crystal structure having an average particle size of 3 to 10 μm
~ 20%, organic binder 3 ~ 15% (in each case wt%)
Then, the clay-like material is kneaded with the material and molded at a normal temperature into a circular tube having a predetermined diameter and a predetermined thickness by extrusion molding or a molding method such as slip casting to produce a molded body.

The composition of the molded article is not limited to this, and various compositions generally proposed as the composition of the air electrode can be used. For example, instead of the above-mentioned strontium,
Calcium, magnesium, barium, yttrium,
Lanthanum manganite to which cerium, yttrium, or the like is added can be used.

The tubular flexible molded product obtained by the above-mentioned molding is put into a drying furnace, and the temperature is raised to about 60 ° C., and the moisture content is dried and removed to obtain a dry molded product capable of maintaining its shape.

Then, as shown in FIG. 1, the molded body 10 is placed on a support member 11 having a semicircular cross section fixed horizontally in a firing furnace, and the firing furnace is heated to a predetermined temperature of about 100 to 150 ° C.
The temperature is raised to a firing temperature of about 1300 to 1600 ° C. at a heating rate of about / hour, and firing is performed for a desired time. Thereafter, the temperature is lowered to a normal temperature at a rate of about 100 to 150 ° C./hour to obtain the electrode support tube 12 as shown in FIG.

Here, the material of the support member 11 has high resistance to a high temperature of 1300 to 1600 ° C., which is the firing temperature, and has a property of hardly reacting with the material of the electrode support tube. Ceramics such as magnesia and alumina are used.

A ceramic powder 13 having substantially the same composition as the electrode support tube to be manufactured is provided on the inner peripheral surface of the support member 11.
To prevent the molded body 10 from directly contacting the surface of the support member 11 during firing. The powder 13 has a particle size larger than the particle size of the raw material powder of the molded body 10, and has an average particle size of, for example, about 5 to 15 μm.

Although the electrode support tube 12 thus obtained has the shape shown in FIG. 2, it is held horizontally and fired in a free state without any restriction on thermal expansion / contraction. The gravitational load is not applied locally unevenly, and the porosity can be made almost uniform over the whole,
Further, an electrode support tube having excellent roundness and straightness can be obtained.

Next, a second embodiment of the present invention will be described with reference to FIG. The feature of the second embodiment is that the supporting member 11 'is fixed in a firing furnace in a state where the supporting member 11' is inclined at a predetermined angle of 5 to 20 °, and the molded body 10 is received by this and fired. . Therefore, the other configuration is the same as that of the first embodiment, and the manufacturing conditions and the composition conditions are common, so that the description is omitted.

The reason for holding and firing the compact 10 with the support member 11 'inclined is as follows. First
When the supporting member 11 is in a horizontal state and the molded body 10 is received and fired as in the embodiment described above, the roundness and straightness are both good as described above, and the porosity is uniform over almost the entire length. Although the electrode support tube 12 can be manufactured, since it is baked at a high temperature, the thermal expansion and contraction dimensions are large when the molded body 10 is 1 to 2 m long, and pores are formed in the middle part in the length direction. The porosity tends to be greater than the porosity at both ends.

However, the molded body 10 is
When firing is performed with a certain degree of inclination within a range that does not slide down, the frictional resistance acting on the material during thermal expansion of the molded body 10 can be reduced, so that the uniformity of the porosity is further improved. It is.

[0032]

EXAMPLE A specific example of the method for producing an electrode support tube of a cylindrical solid electrolyte fuel cell according to the present invention will be described.

Example 1 20% water and 10% methylcellulose (all by weight) were added to a fine powder of lanthanum strontium manganite (La (Sr) MnO ₃ ) having an average particle diameter of 5 μm, and kneaded. This was extruded at room temperature to obtain a molded product having a thickness of 2 μm, a diameter of 20 mm, and a length of 1 m. Then, the molded body was placed in a drying furnace and dried at 60 ° C. to remove moisture, thereby obtaining a molded body capable of self-shaping.

On the other hand, the firing furnace has a length of 1.5 m and an inner diameter of 2 mm.
A support member made of alumina having a semicircular cross section of 5 mmφ is fixed horizontally, and the average particle size is 10 μm over the entire inner peripheral surface of the support member.
Of lanthanum strontium manganite was uniformly spread and compacted to a thickness of about 0.1 mm.

Then, the compact is placed on the supporting member, and the temperature is raised to 1500 ° C. at a rate of 100 ° C./hour.
It is baked at this temperature for 5 hours, and then cooled at a rate of 100 ° C. /
The temperature was lowered to room temperature over a period of time to take out a molded body that became an electrode support tube.

The porosity of the obtained electrode support tube was measured by a mercury intrusion method.
%, And a porosity of 28% at both ends, and a substantially uniform porosity over the entire length. Moreover, the roundness and straightness were comparable to those obtained by the conventional method.

<Embodiment 2> In the firing furnace, the length is 1.5 m,
An alumina support member having an inner diameter of 25 mmφ and a semicircular cross section is fixed with a slope of 20 °, and lanthanum strontium manganite powder having an average particle diameter of 10 μm is coated on the entire inner peripheral surface of the support member with a thickness of 0.1 mm. It was spread evenly to the extent and compacted.

The molded body obtained by the same method as in Example 1 was fired under the same conditions as in Example 1. The porosity of the obtained electrode support tube was measured by a mercury intrusion method. The porosity was approximately 28% at both the middle and both ends in the length direction, and the porosity was uniform over the entire length. Roundness,
Straightness was comparable to that obtained by the conventional method.

[0039]

As described above, according to the first aspect of the present invention,
The unsintered compact is held horizontally on a support member in a free state, and is baked, so that thermal expansion and shrinkage are free, the load distribution is not biased, and porosity is maintained while maintaining roundness and straightness. It is possible to obtain a uniform electrode support tube over the entire length, and furthermore, by laying powder having substantially the same composition as the electrode support tube on the inner periphery of the support member, the molded body and the support member do not come into direct contact, The problem that a chemical reaction occurs between the surface of the support member and the surface of the electrode support tube during high-temperature sintering and thus impairs the electrochemical characteristics of the electrode support tube can be prevented beforehand.

According to the second aspect of the present invention, the unsintered compact is held in a free state on the support member fixed at a predetermined inclination angle and is calcined. It is possible to reduce the frictional resistance acting on the material when expanding and contracting, and to manufacture an electrode support tube having a uniform porosity over the entire length while maintaining roundness and straightness. As in Item 1, the problem that a chemical reaction occurs between the surface of the support member and the surface of the electrode support tube during high-temperature firing, thereby impairing the electrochemical characteristics of the electrode support tube can be prevented beforehand.

According to the third aspect of the present invention, it is possible to obtain an electrode support tube made of a lanthanum-manganese-based oxide ceramic having excellent electrochemical characteristics as a fuel cell electrode.

According to the fourth aspect of the present invention, since powder having substantially the same composition as that of the electrode support tube is interposed between the molded body serving as the electrode support tube and the support member, the powder is interposed between the compact and the support member surface during high-temperature firing. Thus, it is possible to reliably prevent the occurrence of a chemical reaction and obtain a product having excellent electrochemical characteristics.

According to the fifth aspect of the present invention, by making the particle size of the powder spread on the support member larger than the particle size of the raw material powder, the powder spread on the support member during high-temperature firing is reduced. Reaction with the surface of the electrode support tube can be prevented, and the electrochemical characteristics of the electrode support tube can be improved.

According to the sixth aspect of the present invention, since the supporting member is made of heat-resistant ceramics of stabilized zirconia, magnesia, alumina or a mixture thereof, the surface state is stable during high-temperature firing, and The electrochemical properties of the electrode support tube can be improved in combination with the powder interposed between the electrode support tube and the body.

[Brief description of the drawings]

FIG. 1 is a partially broken perspective view showing a state in which a molded body according to a first embodiment of the present invention is supported by a support member.

FIG. 2 is a perspective view of an electrode support tube manufactured according to the embodiment.

FIG. 3 is a partially broken perspective view showing a state in which a molded body according to a second embodiment of the present invention is supported by a support member.

FIG. 4 is a perspective view of a general cylindrical solid electrolyte fuel cell.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Molded body 11, 11 'Support member 12 Electrode support tube 13 Powder

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masakatsu Nagata 1-5-1 Kiba, Koto-ku, Tokyo Inside Fujikura Co., Ltd. (72) Inventor Namiko Kanda 1-5-1 Kiba, Koto-ku, Tokyo Fujikura Co., Ltd. Inside

Claims (6)

[Claims] 1. A powder having a composition substantially the same as that of a target electrode support tube is laid on an inner peripheral surface of a support member made of a high-heat-resistant material having a semicircular cross section fixed horizontally in a firing furnace, An unfired molded body that becomes the electrode support tube by the baking treatment is held by the support member in a free state, and the molded body is fired by raising the temperature of the firing furnace to obtain the electrode support tube. A method for manufacturing an electrode support tube for a cylindrical solid electrolyte fuel cell. 2. A substantially same composition as an intended electrode support tube is provided on an inner peripheral surface of a support member made of a long heat-resistant material having a semicircular cross section and fixed in a firing furnace at a predetermined inclination angle. , And the unfired molded body that becomes the electrode support tube by the firing treatment is held by the support member in a free state. The temperature of the firing furnace is increased to fire the molded body, and the electrode support is fired. A method for producing an electrode support tube for a cylindrical solid electrolyte fuel cell, comprising obtaining a tube. 3. A green body obtained by kneading a lanthanum manganese-based fine powder having a perovskite crystal structure, water and a binder to form a clay-like material and drying the formed body, followed by drying to remove moisture. The method for producing an electrode support tube of a cylindrical solid electrolyte fuel cell according to claim 1 or 2, wherein: 4. The method according to claim 3, wherein a ceramic powder of a lanthanum manganese-based oxide is used as the powder to be spread on the support member. 5. The electrode support for a cylindrical solid electrolyte fuel cell according to claim 4, wherein the powder to be spread on the support member has a particle size larger than that of the raw material powder. Tube manufacturing method. 6. The cylindrical solid electrolyte fuel according to claim 1, wherein the support member is made of a heat-resistant ceramic made of stabilized zirconia, magnesia, alumina or a mixture thereof. A method for manufacturing an electrode support tube for a battery.